Add SqlGlot dialect for LegendQL with DuckDB integration

[neema2]

Add SqlGlot dialect for LegendQL with DuckDB integration

This PR adds a new SqlGlot backend/dialect to translate the LegendQL metamodel to SQL using the sqlglot library in Python. The implementation focuses on the FROM and SELECT operations, enabling LegendQL to query DuckDB tables through SqlGlot SQL translation.

Features

• Implemented SqlGlotRuntime and SqlGlotExpressionVisitor classes to translate LegendQL metamodel to SqlGlot expressions
• Added DuckDBSqlGlotRuntime for executing SqlGlot-generated SQL against DuckDB
• Created comprehensive test cases for simple SELECT and filtered SELECT queries
• Mapped metamodel concepts (from, select, filter) to SqlGlot expressions

Testing

• Added unit tests that verify SQL generation and query execution
• Tests confirm correct translation of LegendQL queries to SQL
• Verified execution against a test DuckDB database

Implementation Details

• Created new directory structure for SqlGlot dialect implementation
• Fixed connection handling in DuckDB implementation
• Ensured proper type handling for SQL literals

Requested by: neema.raphael@gs.com
Link to Devin run: https://app.devin.ai/sessions/7ae3797bce3648ef8df9704fecc4ff01